Self-contained issues

[elegios]

The python library currently defaults to using an installed tpplc, which might be confusing if you have an old version. We should consider what we want the default to be, and how we might override it, if that's desired.

It also appears that the self-contained version of tpplc isn't quite independent of certain environment variables, notably MCORE_LIBS, which means it might use an installed library instead of the one in the self-contained package.